Numerous electronic transactions systems are known that make use of portable information media The. best known comprise payment systems based on memory cards. Other systems use electronic keys. When appropriately programmed, such portable information media give their holders access to goods or services provided by an operator, such as a pay-phone, electricity, or television.
At present, portable electronic transaction media are manufactured in very large quantities at centralized production sites, and then they are delivered ready for use to an operator or to a distribution center which then passes them on to carriers. Naturally, in the event of theft, said media can be sold beyond the control of the operator.
Various means of providing protection against this risk have been conceived, such as physical protection during transport, which nevertheless turns out to be insufficient since it is expensive, inconvenient, and does not always provide a genuine guarantee.
Identifying stolen media by means of a stop list assumes that reader devices have the capacity to process long lists, and often that is not the case.
Finally, transporting media in small batches does indeed limit the risk, but it makes costs and deadlines unacceptable for large volumes.
Also, for portable information media provided with a firmware electronic component, such as prepaid phone cards, a security technique is known whereby a transport code programmed by the manufacturer of the firmware electronic component makes it possible to ensure that only the manufacturer of media for whom the component is intended will be able to use it.
To extend this service to transport between the manufacturer of the media and the operator-client, it would suffice if the manufacturer did no programming, leaving that to the operator-client. However, such a system would suffer from the major drawback that the transport code could not be given to the operator for reasons of confidentiality unless the media manufacturer were to provide components having different codes as a function of different clients. That solution would lead to very expensive and difficult logistic constraints.